FAQ: Does WebMarshal support Byte Ranges?

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This article applies to:

  • WebMarshal


  • HTTP requests can include a Byte Range header. This header allows transfer of a specific portion of a file.
  • Does WebMarshal support Byte Range requests?
  • Why does WSUS not work through WebMarshal?


WebMarshal does not allow use of Byte Ranges. Reliable content analysis requires the entire file to be available.

WebMarshal removes the Byte Range header from requests. In most cases the entire file will be requested and served.

Some applications that use Byte Ranges may not work.

  • For instance some applications download an initial setup stub which in turn downloads selected extra portions.
  • The Microsoft WSUS (Windows Server Update Services) service uses byte ranges when running in background mode.
  • Other applications that use Microsoft BITS (Background Intelligent Transfer Service) also use byte ranges.

If you encounter problems with applications that use byte ranges, you can add the sites into the WebMarshal proxy bypass list. Requests to sites in this list will not pass through the WebMarshal filter. The Range header will not be stripped and Byte Range functions should work as expected.

However, file content will not be checked by the WebMarshal rules.


Use the bypass feature with caution, and only for trusted sites. WebMarshal does not perform any virus or malware checking for sites in the bypass list.

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